Thread (29 messages) 29 messages, 4 authors, 2020-12-28
STALE2026d REVIEWED: 5 (5M)
Revisions (3)
  1. v3 [diff vs current]
  2. v4 [diff vs current]
  3. v5 current

[PATCH v5 03/15] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched EL0 support

From: Will Deacon <will@kernel.org>
Date: 2020-12-08 13:30:02
Also in: linux-arch, lkml
Subsystem: arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers: Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds

If a vCPU is caught running 32-bit code on a system with mismatched
support at EL0, then we should kill it.

Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/arm.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index c0ffb019ca8b..e63e8feae836 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -649,6 +649,15 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu)
 	}
 }
 
+static bool vcpu_mode_is_bad_32bit(struct kvm_vcpu *vcpu)
+{
+	if (likely(!vcpu_mode_is_32bit(vcpu)))
+		return false;
+
+	return !system_supports_32bit_el0() ||
+		static_branch_unlikely(&arm64_mismatched_32bit_el0);
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:	The VCPU pointer
@@ -832,7 +841,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		 * with the asymmetric AArch32 case), return to userspace with
 		 * a fatal error.
 		 */
-		if (!system_supports_32bit_el0() && vcpu_mode_is_32bit(vcpu)) {
+		if (vcpu_mode_is_bad_32bit(vcpu)) {
 			/*
 			 * As we have caught the guest red-handed, decide that
 			 * it isn't fit for purpose anymore by making the vcpu
-- 
2.29.2.576.ga3fc446d84-goog


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